Diffusion transfer elements comprising color-providing compounds capable of cleavage upon reaction with silver ions and silver ion barrier layers

ABSTRACT

A silver ion scavenger layer is employed between adjacent silver halide strata to enhance color separation in multicolor photographic images prepared by processes which utilize the imagewise distribution of silver ions and/or soluble silver complex made available during development to liberate a corresponding imagewise distribution of dye or dye intermediate from a color-providing compound.

BACKGROUND OF THE INVENTION CROSS REFERENCE TO RELATED PATENTAPPLICATIONS

This application is a continuation-in-part of our copending U.S.Application Ser. No. 465,694 filed Apr. 30, 1974, now abandoned, whichis a continuation-in-part of our U.S. application Ser. No. 317,168 filedDec. 21, 1972, now abandoned, which in turn is a division of our U.S.application Ser. No. 155,123 filed June 17, 1971 and now U.S. Pat. No.3,719,489 issued Mar. 6, 1973.

1. FIELD OF THE INVENTION

This invention relates to photography, and more particularly, tophotographic products and processes for preparing color images utilizingas the dye image-forming material, a color-providing compound capable ofundergoing cleavage in the presence of an imagewise distribution ofsilver ion and/or soluble silver complex to liberate a correspondingimagewise distribution of color-providing moiety, e.g., a dye.

2. DESCRIPTION OF THE PRIOR ART

Diffusion transfer photographic processes are now well-known. Inpreparing silver images according to such processes, an exposedphotosensitive element comprising a light-sensitive silver halideemulsion is developed by treating the emulsion with a processingcomposition comprising an aqueous alkaline solution of a silver halidedeveloping agent and a silver halide solvent. The developable silverhalide of the emulsion is reduced to image silver by the developingagent while the silver halide solvent forms an imagewise distribution ofa soluble complex with the undeveloped silver halide. This imagewisedistribution of soluble silver complex is, at least in part, transferredby imbibition to a superposed image-receiving layer where it is reducedto form a silver transfer image.

Aforementioned U.S. Pat. No. 3,719,489 describes and claims photographicprocesses employing certain photographically inert compounds which arestable in the photographic processing composition but capable ofundergoing cleavage in the presence of the imagewise distribution ofsilver ions made available during processing of a silver halide emulsionto liberate a reagent, such as, a photographically active reagent or adye in an imagewise distribution corresponding to that of said silverions. Depending upon the photographic process and the result it isdesired to achieve the inert parent compound may be diffusible orsubstantially non-diffusible in the processing solution and the reagentliberated also may be diffusible or substantially non-diffusible in theprocessing composition.

In one embodiment disclosed in the aforementioned patent, color imagesare produced by using as the photographically inert compounds,color-providing compounds which are substantially non-diffusible in thephotographic processing solution but capable of undergoing cleavage inthe presence of the imagewise distribution of silver ions and/or solublesilver complex made available in the undeveloped and partially developedareas of a silver halide emulsion as a function of development toliberate a more mobile and diffusible color-providing moiety in animagewise distribution corresponding to the imagewise distribution ofsaid ions and/or said complex. The subsequent formation of a color imageis the result of the differential in diffusibility between the parentcompound and liberated color-providing moiety whereby the imagewisedistribution of the more diffusible color-providing moiety released inundeveloped and partially developed areas is free to transfer.

Both monochromatic and multicolor images may be produced in this manner.For example, the above-described color-providing compounds may beemployed in photographic systems utilizing integral multilayerphotosensitive elements comprising at least two selectively sensitizedsilver halide emulsion strata with associated color-providing materialwhich are processed simultaneously and without separation to provide amulticolor image on a single common image-receiving element.

Among the compounds disclosed as useful in liberating a reagent in thepresence of silver ion are sulfur-nitrogen compounds containing thegroup, ##STR1## wherein X is ##STR2## These compounds may be linear orcyclic in structure, and when cyclic, either or both the S and N atomsmay be constituents of the ring. Particularly useful are cycliccompounds containing the group ##STR3## as part of the ring andpreferably, the latter. Like 1,3-sulfur-nitrogen compounds, in general,these compounds undergo cleavage in a stepwise fashion between the Satom and the C atom common to the S and N atoms and also between the Natom and the common C atom.

As discussed in the aforementioned patent, sulfur-nitrogen compounds, asexemplified by thiazolidine compounds, exhibit good stability inalkaline media, such as the aqueous alkaline processing compositionsemployed in conventional "tray" and diffusion transfer photographicprocesses, and undergo cleavage in the presence of silver ions and/orsoluble silver complex made available during processing to release areagent as a smaller molecule in an imagewise distribution correspondingto the imagewise distribution of silver ions and/or soluble silvercomplex. For example, thiazolidine compounds release a diffusible dyesuch that a diffusion transfer image is obtained in reasonableprocessing times.

The present invention is concerned with photographic processes of thistype and with photographic products useful therein for producingmulticolor images of improved quality.

SUMMARY OF THE INVENTION

It is the primary object of the present invention to providephotographic products and processes of the foregoing description forproducing multicolor images exhibiting improved color separation andwhiter highlights.

Another object of this invention is to provide photographic productscomprising a photosensitive element particularly an integral multilayerphotosensitive element having at least one layer of scavenger for silverion and/or soluble silver complex.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationand order of one or more such steps with respect to each of the others,and the product possessing the features, properties and the relation ofelements, which are exemplified in the following detailed disclosure,and the scope of the application which will be indicated in the claims.

For a fuller understanding of the nature and object of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is an enlarged, diagrammatic, fragmentary sectional view ofone product contemplated by this invention during processing thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As mentioned previously, the present invention is concerned with thepreparation of color photographic images by utilizing the imagewisedistribution of silver ions and/or soluble silver complex made availableduring development of a photosensitive element to liberate acorresponding imagewise distribution of a dye or dye intermediate from acolor-providing compound. It has now been found that improved colorseparation may be achieved in the production of multicolor images byincluding in the photosensitive element, one or more layers containing ascavenger for silver ion and/or soluble silver complex to confinediffusion of the imagewise distribution of silver ions and/or solublesilver complex made available during development to the appropriatelayer of color-providing compound. In addition to the improvement incolor separation, the inclusion of such a layer or layers in an integralmultilayer photosensitive element provides multicolor images havingimproved highlights.

In the present invention, any material may be used as the silverscavenger layer that is capable of capturing silver ion and/or solublesilver complex provided, of course, that the layer is permeable to theprocessing reagents, e.g., the silver halide developing agent and silverhalide solvent and allows color-providing moiety to diffuse through toform a multicolor diffusion transfer image. Useful materials includesilver complexing agents and compounds that generate silver complexingagents which form stable, preferably non-diffusible complexes withsilver ion and keep the silver ion in the same oxidation state andsilver precipitating agents that reduce silver ion to metallic silver.Examples of specific materials that may be employed for forming stable,non-diffusible complexes with silver ion and/or soluble silver complexare polymers containing recurring mercapto-substituted tetrazolemoieties such as those forming the subject matter of copending U.S.patent application Ser. No. 520,983 of Michael J. Grasshoff and JeromeL. Reid filed Nov. 5, 1974, now U.S. Pat. No. 3,936,401 issued Feb. 2,1976, and polymers containing recurring mercapto-ethylamine moietiessuch as those forming the subject matter of copending U.S. patentapplication Ser. No. 574,295 of Louis Locatell, Jr. filed concurrentlyherewith and now U.S. Pat. No. 4,021,416 issued May 3, 1977. Silverprecipitating agents useful in this invention may be readily selectedfrom among the many materials taught in the art to be useful asnucleating agents in silver transfer processes. Examples of particularlysuitable silver precipitating agents are the metallic sulfides andselenides and colloidal metals disclosed in U.S. Pat. No. 2,698,237.Other useful materials are compounds which react with silver ion to forma complex that decomposes to provide a nucleating agent, and/or a silvercomplexing agent. Illustrative of such compounds are polymers containingrecurring thiourea moieties such as those described by C. G. Overbergeret al., Journal of Polymer Science: Part A, Vol. 3, pp. 3625-3634(1965). The reaction of thiourea and its derivatives with silver saltsand the decomposition reaction of the resulting thiourea-silver saltcomplex with the deposition of silver sulfide has been described by B.Javor, Kemija i Industrija (Zagreb) 14, (g), pp. 739-742 (1965). As willbe readily apparent suitable precautions should be taken to insure thatthe silver ion scavenger be confined to its own layer for cases in whichthe particular scavenger selected might adversely affect thesensitometry.

In forming color images according to one embodiment of the presentinvention, a relatively non-diffusible color-providing compound ispresent, for example, in a layer associated with each of at least twoselectively sensitized silver halide emulsion layers and a silverscavenger layer is provided between the two emulsion layers. Theemulsion layers, after being exposed, are processed simultaneously andwithout separation by the application of an aqueous alkaline processingsolution including a silver halide developing agent and a silver halidesolvent. The imagewise distribution of silver ions such as contained inthe soluble silver complex made available during processing of eachemulsion layer migrates to the color-providing material associated withthe emulsion and the color-providing material undergoes cleavage in thepresence of the complex to provide an imagewise distribution of a morediffusible color-providing moiety. By virtue of the silver scavengerlayer positioned between the two emulsion layers, the migration of theimagewise distribution of soluble silver complex formed duringprocessing of each emulsion layer is confined to the color-providingmaterial associated with each emulsion and prevented from diffusing intothe color-providing material associated with the other emulsion layer orlayers. The subsequent formation of a color image is the result of adifferential in diffusibility between the parent material and liberatedcolor-providing moiety whereby the imagewise distribution of the morediffusible color-providing moiety released in undeveloped and partiallydeveloped areas is free to transfer. For example, where thenon-diffusible parent material is colored, e.g., comprises a completedye, the imagewise distribution of diffusible dye released therefrom maybe simply washed away to leave an image associated with the emulsion, orit may be transferred by imbibition to an image-receiving layer, e.g., adyeable stratum of the character heretofore known in the art to providea color transfer image thereon.

The respective mobility characteristics of the parent compound and ofthe liberated color-providing moiety may be substantially the same, orthey may be different as appropriate for a given photographic process. Adifferential in diffusibility between the parent compound and the moietyliberated therefrom may be achieved in various ways, for example, byusing a normally immobile and non-diffusible parent compound which uponcleavage releases a diffusible color-providing moiety, or conversely, byusing a normally mobile parent compound which upon cleavage releases acolor-providing moiety that is substantially non-diffusible.

To be useful in the present invention, the parent compound should bephotographically inert and stable in the processing solution, i.e.,should remain intact in the processing composition in the absence ofsilver ion at least during the processing interval, but should becapable of undergoing cleavage in the presence of the imagewisedistribution of silver ions and/or the imagewise distribution of solublesilver complex containing silver ions made available as a function ofdevelopment to release a color-providing moiety, such as, a dye. Itsrate of cleavage in the presence of silver ion, however, should be suchthat an imagewise distribution of color-providing moiety is obtainedthat corresponds to the imagewise distribution of silver ions or solublesilver complex formed in the partially exposed and unexposed areas ofthe emulsion. If the rate of cleavage is excessive, color-providingmoiety may be released to some extent in the exposed areas.

Illustrated below are examples of compounds which may be used to releasea color-providing moiety and the silver accelerated cleavage reactionswhich they undergo. ##STR4##

For use in the present invention, the above compounds may beappropriately substituted with the desired color-providing moiety it isdesired to liberate and with other group (s) as may be necessary toachieve a differential in diffusibility between the uncleaved parentcompound and the moiety released therefrom. Where such a differential indiffusibility is necessary or desired for the particular photographicprocess, the parent color-providing compound may be substituted with animmobilizing group or "anchor", that renders the compound substantiallynon-diffusible in the processing solution, or, rather than a singleimmobilizing group, the parent color-providing compound may besubstituted with two or more groups which together preclude migration ofthe compound from its position in the photographic element. When severalgroups together are used to immobilize the compound, one or more of thegroups may be on the fragment to be released as a diffusible reagent solong as the group(s) does not reduce to any appreciable extent themobility and diffusibility of the fragment subsequent to cleavage.

It will be appreciated that where a single immobilizing group is used toanchor the color-providing compound, its position on the compound shouldbe such that upon cleavage, it will be on a fragment different from thefragment to be released as the diffusible color-providing moiety.Depending upon the photographic process used and upon the location ofthe parent compound in the photographic element, it may be preferable toposition the immobilizing group on that portion of the parent compoundthat ultimately forms a complex with the silver ion. For example, whenproducing positive transfer images using diffusion transfer techniques,it is preferred to anchor the fragment that will complex the silver ionin the photosensitive element to avoid possible staining of the colorimage formed in the image-receiving sheet.

The selection of a particular immobilizing group(s) for anchoring theparent compound will depend primarily on whether it is desired to employonly one immobilizing group or to employ two or more groups whichtogether are capable of anchoring the compound. Where two or more groupsare employed to immobilize the compound, lower alkyl groups, butyl orhexyl, for example, may be used to achieve the requisite differential indiffusibility between the parent color-providing compound and thecolor-providing moiety released therefrom. Where only one group is usedto immobilize the compound, it is more effective to employ, for example,a higher alkyl radical such as octyl, decyl, dodecyl, stearyl, and oleylor a carbocyclic or heterocyclic ring having six members or more. Wherecyclic compounds are employed, the carbocyclic or heterocyclicimmobilizing group may be bonded to a single atom or to adjacent atomsof the parent molecule and may be bonded to a single atom by a valenceor ionic bond or through a spiro union.

As the "color-providing moiety" in forming color images according to thepresent invention, there may be used a complete dye or a dyeintermediate capable of yielding a complete dye upon subsequentreaction, for example, upon reaction with a suitable coupler to form acomplete dye. The coupling reaction may take place directly in theimage-receiving layer, or it may take place in the emulsion layer or inthe layer of processing composition after which the complete dye formeddiffuses to the image-receiving layer.

Complete dyes which may be used as the color-providing moiety maycomprise any of the general classes of dyes heretofore known in the art,for example, nitro, indophenol, indoaniline, anthraquinone, azomethine,anthrapyridone, azo, thiazole, di- and triphenyl methane, cyanine,phthalocyanine and metal-complexed azo, azomethine and phthalocyaninedyes. Dye intermediates include any molecule which when released iscapable of forming a dye upon reaction with another molecule. Forexample, an imagewise distribution of a dye intermediate may be releasedfrom a 1,3-sulfur-nitrogen compound, e.g., a thiazolidine, whichimagewise distribution of dye intermediate in turn reacts with anothermolecule to produce a corresponding imagewise distribution of completedye. Photographic processes and products utilizing dye-forming systemswherein an imagewise distribution of a complete dye is produced by thereaction of an aldehyde or ketone dye intermediate and a color-formingreagent, such as, a methylene coupler comprises the subject matter ofU.S. Pat. No. 3,719,488 of Louis Locatell, Jr., Frank A. Meneghini andHoward G. Rogers.

The color-providing moiety, whether a complete dye or dye former, may belinked directly to an atom of the parent molecule by a valence or ionicbond or through a spiro union, or it may be linked indirectly to theparent molecule through an appropriate linking group either acyclic orcyclic. Typical linking groups include cycloalkyl, such as cyclohexyl;--CONH --; --alkylene--CONH--; arylene--CONH--; alkylene; and arylenewherein alkylene may be ethylene, propylene, butylene and arylene may bephenylene. The term color-providing moiety as used herein includes anylinking group and the moiety may contain on the color-providing and/orlinking portion various solubilizing substituents, e.g., sulfo, hydroxylor carboxyl groups to adjust its solubility characteristics.

In addition to the above, useful dyes include those which are colorlessor of a color other than that ultimately desired in a certainenvironment, such as at a particular pH level, but upon a change inenvironment, e.g., from acid to alkaline conditions, take on a colorchange. Color-providing materials of this nature include indicator dyesor leuco dyes. It is also contemplated that dyes may be employed whichundergo a color shift or change in spectral absorption characteristicsduring or after processing. Such dyes may be referred to as "temporarilyshifted" dyes. The temporary shift may, for example, be effected byacylation, the acyl group being removable by hydrolysis in the alkalineprocessing composition. It is also within the scope of the presentinvention to employ metal complexed or complexable dyes and to employdyes, the non-complexed forms of which are substantially colorless, butwhich, when complexed during or subsequent to image formation, are ofthe desired color.

Though some of the compounds enumerated above may cleave in the absenceof silver ion under extreme conditions, such as strong heating, they aresufficiently stable under neutral, acid and alkaline conditions atambient temperatures to remain intact under the processing conditionsencountered in conventional and diffusion transfer photography untilsilver ion becomes available as a function of development. However, thereactivities of the various compounds toward silver ion may vary andthus, some compounds may cleave more rapidly in the presence of silverion than others. Accordingly, it will be appreciated that the particularcompound selected should have the cleavage rate necessary for obtainingan imagewise distribution of color-providing moiety under the particularprocessing conditions employed. In diffusion transfer processes, it isdesirable that the parent compound cleave in the presence of silver ionand/or soluble silver complex containing silver ion to release adiffusible color-providing moiety such that a transfer image is obtainedwithin a reasonable processing time.

Of the aforementioned classes of compounds, the 1,3-sulfur-nitrogencompounds have been found especially satisfactory. As discussed above,these compounds may be linear, or they may be cyclic in structure witheither or both of the S and N atoms being constituents of the ring whichshould contain at least four atoms. The compounds may be saturated orunsaturated provided the S and N atoms each are bonded to the common,i.e., intermediate, carbon atom by a single bond.

Among the 1,3-sulfur-nitrogen compounds that may be used in the presentinvention are those represented in the following formulae: ##STR5##wherein R₁ and R₅ each are a monovalent organic radical and R₂, R₃ andR₄ each are hydrogen or a monovalent organic radical; ##STR6## whereinR₂, R₃ and R₄ have the same meaning as in formula (I) above; R₆ and R₇on the same or different atoms each are hydrogen or a monovalent organicradical and taken together represent a substituted or unsubstitutedcarbocyclic or heterocyclic ring; Z represents the atoms, preferablycarbon atoms, necessary to complete a ring system having up to 20members; ##STR7## wherein R₂, R₃, R₄, R₆, R₇ and Z have the same meaningas in formula (II) above; and ##STR8## wherein R₂, R₃, R₆, R₇ and Z havethe same meaning as in formula (II) above.

Examples of cyclic compounds which may be used in the present inventionare thiazolidines, tetrahydro-1,3-thiazines, benzothiazolines,benzimidazolines, tetrahydrothiophenes, s-thithianes, 1,3-dithianes,tetrahydrothiopyrans, 1,3-dithiolanes, pyrrolidines, imidazolidines,hexahydro-s-triazines, piperazines, piperidines, and morpholines. Wherethe ring contains a nitrogen atom but no sulfur atom or where the ringcontains a sulfur atom but no nitrogen atom, the compound will beappropriately substituted with a sulfur or nitrogen-containing group toobtain the 1,3-sulfur-nitrogen configuration. For example, in Formula(IV) above, the sulfur-nitrogen configuration may be obtained byselecting as the R₂ or R₃ group, a monovalent organic radical ##STR9##wherein R₄ and R₅ have the same meaning given above and R is a divalentorganic radical. Likewise, the desired configuration may be obtainedwith compounds of formula (III) by selecting as R₄, a monovalent organicradical ##STR10## or by selecting as the R₂ or R₃ group, a monovalentorganic radical -- S -- R₁ wherein R₁ has the same meaning given above.It will be appreciated that the compound may contain more than onesulfur-nitrogen configuration if desired. As an illustration, thecompound of formula (II) may be substituted with a cyclic1,3-sulfur-nitrogen substituent in the 2-position through a linkinggroup, such as a methylene group, to give, e.g., a bis compound.

It will be understood that at least one of the substituents of thecompounds illustrated in the above formulae will be the color-providingmoiety it is desired to release from the parent compound, which moietymay be released as an amine, aldehyde, ketone, etc., depending upon theposition of the substituent on the parent. Also, one or more of the Rsubstituents may be selected to immobilize the compound in processeswhere it is desired to render the uncleaved parent compoundsubstantially non-diffusible in the processing solution, or one or moreof the R substituents may be selected to enhance the solubility of thecompound in processes where it is desired to render the parent compounddiffusible in the processing solution. Suitable immobilizing andsolubilizing groups have been enumerated above. The positioning of thesegroups on the parent color-providing compound will depend upon thediffusionibility characteristics desired for the parent compound and forthe color-providing moiety released upon cleavage in a given process. Asnoted previously, the parent and the moiety liberated therefrom mayexhibit the same diffusibility characteristics in the photographicprocessing solution. For example, in one embodiment of the process ofaforementioned U.S. Pat. No. 3,719,488, both the parent and dyeintermediate released therefrom may be non-diffusible so that thecomplete dye formed upon reaction with the color-forming reagent remainsin the photosensitive element to provide a color image therein. Thediffusibility characteristics also may be different. For example, theparent compound may be non-diffusible and comprise a complete dye whichdye is released as a more diffusible fragment that is transferred to adye image-receiving element to provide a color transfer image thereon.In addition to the immobilizing and/or solubilizing groups, it will beappreciated that R groups may comprise other substituents which do notinterfere with its intended use.

Typical of the substitutents that may be used in the above formulaeinclude carboxy, sulfo, nitro, hydroxy, halo, e.g., chloro and bromo,cyano and hydrocarbon radicals including aliphatic, cycloaliphatic,aromatic and heterocyclic radicals. The radicals may possess ethylenicor acetylenic unsaturation, and the carbon chains may be interrupted byheteroatoms or heteroatom groups, such as, S, O, N, SO, NH and so forth.Also, the radicals may contain substituents, e.g., phenyl, alkyl, alkylether, aryl ether, carbalkoxy, carboxy, hydroxy, sulfo, halo, cyano,nitro, and alkylamino.

Examples of suitable radicals are substituted and unsubstituted alkylgroups, such as, methyl, ethyl, otcyl, dodecyl; substituted andunsubstituted cycloalkyl radicals, such as, cyclohexyl, cyclopentyl,cyclooctyl; substituted and unsubstituted alkenyl groups, such as,vinyl, allyl, butenyl, decenyl, octadienyl, hexatrienyl; substituted andunsubstituted cycloalkenyl groups, such as, cyclopentenyl,cycloheptenyl, cyclohexadienyl; substituted and unsubstituted alkynylgroups, such as, ethynyl, hexynyl, octynyl; substituted andunsubstituted aryl radicals, such as, phenyl, tolyl, benzyl andnaphthyl; and substituted and unsubstituted heterocyclic groups, such asthose having a 4-, 5- or 6 -membered ring and containing O, N, S, andcombinations thereof derived from, e.g., pyrrole, pyrazole, oxazole,thiazole, imidazole, pyrimidine, piperidine, piperazine, thiophene,pyrrolidine, azetidine. Where a single hydrocarbon moiety is used as theimmobilizing group, higher acyl radicals such as oleoyl and stearoylgroups have been found useful.

It will be appreciated by those skilled in the art that the vinyl andphenylene analogs of the above sulfur-nitrogen compounds, includingthose exemplified in formulae (I) - (IV), are useful in the presentinvention. The 1,3-sulfur-nitrogen compounds and their vinyl andphenylene analogs may be defined as containing the group, ##STR11##wherein X is ##STR12## As in the compounds illustrated in formulae (I) -(IV), the above analogs may be substituted with an immobilizing groupand/or a solubilizing group and with a color-providing moiety.

Compounds found especially suitable for forming images by diffusiontransfer are certain cyclic sulfur-nitrogen compounds where both the Sand N atoms are included in the ring, particularly thiazolidines andbenzothiazolines. These compounds exhibit the desired stability in theprocessing composition, and in the presence of silver ions undergocleavage at the desired rate to release a reagent, e.g., acolor-providing moiety in an imagewise distribution corresponding tothat of the silver ions and/or soluble silver complex containing thesame made available in the undeveloped areas of the emulsion. Besidesexhibiting these characteristics under the highly alkaline conditionsordinarily employed in diffusion transfer processes, they may beemployed under neutral and acid conditions as well.

Illustrative of the aforementioned cyclic compounds particularly usefulin forming dye images are those represented in the following formulae(V) and (VI), and preferably (VI). ##STR13## wherein R₂, R₃, R₄ and Zhave the same meaning given above. It will be appreciated that the ringsystem represented by Z may be substituted if desired as in theillustrative compounds of formulae (I) and (IV). When using thesecompounds in the production of dye images, the color providing moiety ispreferably but not necessarily substituted on the carbon atom common tothe sulfur and nitrogen atoms where the formation of the color image isbased on a difference in diffusibility between the parentcolor-providing compound and the liberated color-providing moiety andthe color-providing moiety selected as the organic radical R₂ and/or R₃is a diffusible dye, then R₄ and/or a group or groups substituted on thering Z should be capable of rendering the parent compound substantiallyimmobile in the photographic processing solution. Alternatively, if thecolor-providing moiety is a non-diffusible dye, the R₄ and/or group orgroups substituted on Z should be capable of rendering the parentcompound diffusible in the processing solution.

Specific examples of color-providing compounds comprising a completedye, i.e., a dye radical comprising the chromophoric system of a dye anda cyclic moiety, containing the group ##STR14## included in the ring arethose compounds designated formulas (1) to (36) in col. 18, line 29through col. 22, line 48 of aforementioned U.S. Pat. No. 3,719,489.These color-providing commpounds form the subject matter ofaforementioned U.S. patent application Ser. No. 465,694 and aredescribed in detail on specification pages 37-81 thereof whichdescription, for convenience, is specifically incorporated herein byreference.

In the present invention, the parent color-providing compound may bepresent in the photosensitive element in the photosensitive layer itselfif the compound is inert, that is photographically innocuous in that itdoes not adversely affect or impair image formation to any appreciableor unacceptable extent. If not photographically innocuous, the compoundmay be modified in a mamnner which does not interfere with thedevelopment process in any way, but which deactivates the compound sothat it does not affect adversely the light-sensitive emulsion. Also,the parent color-providing compound may be contained in a layer separatefrom the silver halide emulsion, for example, in a layer behind theappropriate silver halide emulsion and if desired, may be separated fromthe emulsion layer by one or more spacer layers.

As noted above, the present invention is concerned with the productionof multicolor images by employing a film unit containing at least twoselectively sensitized silver halide emulsion layers each havingassociated therewith a color-providing compound of the type describedabove which exhibits the desired spectral absorption characteristics.The most commonly employed elements of this type are the so-calledtripack structures employing a blue-, a green- and a red-sensitivesilver halide emulsion having associated therewith, respectively, ayellow, a magenta and a cyan color-providing material wherein thephotosensitive strata and their respective associated color-providingmaterials are superposed on a single support and processedsimultaneously and without separation. In the production of colortransfer images, this integral multilayer photosensitive element isprocessed with a single, common image-receiving layer. For a fullerunderstanding of the photographic products to which the presentinvention is directed, reference should be had to the accompanyingdrawing.

The FIGURE shows one such photographic product during processing thereofto form a color transfer image. As shown in the FIGURE, the photographicproduct [which has been selectively exposed ] comprises a support 14,carrying a layer 15 containing a cyan color-providing compound; a layer16 comprising a red-sensitive gelatino silver halide emulsion; a silverscavenger layer 17; a layer 18 containing a magenta color-providingcompound; a layer 19 comprising a green-sensitive gelatino silver halideemulsion; a second silver scavenger layer 20; a layer 21 containing ayellow color-providing compound; a layer 22 comprising a blue-sensitivegelatino silver halide emulsion; and a protective overcoat or auxiliarylayer 23.

This photosensitive element is shown to be in processing relationshipwith an image-receiving element comprising a support 25 carrying animage-receiving layer (dyeable stratum) 24. A liquid processingcomposition 12 is shown to be disposed between the superposedphotosensitive and image-receiving elements. In exposed areas of theemulsion layers 16, 19 and 22, silver halide is reduced to image silverwhile an imagewise distribution of soluble silver complex is formed interms of unexposed areas. The imagewise distribution of soluble silvercomplex formed in each of the said emulsion layers is, at least in part,transferred by imbibition to the color-providing compound associatedwith each emulsion, i.e., the cyan, magenta and yellow color-providingcompounds of layers 15, 18 and 21, respectively, where the solublesilver complex accelerates cleavage of the color-providing compound torelease a diffusible cyan, magenta and yellow color-providing moiety,for example, a cyan, a magenta and a yellow dye in areas correspondingto the unexposed areas of the respective emulsion layers 16, 19, and 22.The imagewise distributions of diffusible cyan, magenta and yellow dyesproduced in this manner transfer, by diffusion, to the dyeableimage-receiving layer 24 to form a positive multicolor transfer image.Silver scavenger layers 17 and 20 confine the diffusion of solublesilver complex formed in each of the emulsion layers to thecolor-providing material associated with each. The soluble silvercomplex of the red-sensitive emulsion is confined to the cyancolor-providing material, the soluble silver complex of the greensensitive emulsion is confined to the magenta color-providing material,and the soluble silver complex of the blue-sensitive emulsion isconfined to the yellow color-providing material.

Processing composition 12 may be applied to the photosensitive elementby coating, dipping, spraying or any or all of the ingredients thereofmay be confined initially in a frangible container such as disclosed inU.S. Pat. No. 2,543,181, the container being positioned in the film unitso as to be capable upon rupture of releasing its contents for spreadingin a substantially uniform layer between the superposed layers. It willbe appreciated that the respective elements may be placed insuperposition prior to, during or following impregnation with theprocessing composition according to procedures known in the art.

The film structure shown in the FIGURE may be varied, for example, byemploying one or more interlayers between those of the emulsion andcleavable color-providing compound as suggested above, by including ayellow filter, e.g., a layer comprising benzidine yellow in front of thegreen sensitive emulsion or by varying the order of the layers and isintended to be illustrative only of one embodiment structure useful inthe preparation of multicolor images according to the present invention.

Rather than liberating a complete dye as described above, thecolor-providing moiety released may be a dye intermediate which reactswith a reagent such as a methylene coupler to yield a complete dye asdescribed in aforementioned U.S. Pat. No. 3,719,488 which patent, forconvenience, is specifically incorporated herein. In this embodiment, alayer containing color-providing compound and coupler may be associatedwith each of the selectively sensitized emulsion layers in thephotosensitive element and an imagewise distribution of a complete dyehaving the desired spectral absorption characteristics formed uponapplication of the processing composition. To form a transfer image, thedye produced should be capable of diffusing in the processingcomposition. By using a transparent receiving element, the resultingtransfer image, when stripped from the photosensitive element, may beviewed by transmitted light as a transparency. By including anappropriately positioned light-reflecting layer, e.g., of a whitepigment such as titanium dioxide, or means for providing such a layer,the image may be viewed as a reflection print without separating theimage-receiving and photosensitive elements. Color transparencies andreflection prints of this type also may be produced in this manner wherethe diffusible color-providing moiety released is a complete dye.

The following examples are given to illustrate the present invention andare not intended to limit the scope thereof.

EXAMPLE 1

A photosensitive element using as the color-providing compounds torelease a cyan dye and a yellow dye ##STR15## was prepared by coating atransparent polyethylene terephthalate film base with the followinglayers:

1. a layer of cyan color-providing compound dispersed in gelatin andcoated at a coverage of about 60 mgs/ft.² of cyan color-providingcompound and about 60 mgs/ft.² of gelatin;

2. a red-sensitive gelatino silver iodobromide emulsion coated at acoverage of about 35 mgs/ft.² of silver and about 60 mgs/ft.² ofgelatin;

3. a layer of the potassium salt of poly[1-(p-vinyl-phenyl)-1,2,3,4-tetrazole-5-thiol] coated from aqueoussolution at a coverage of about 100 mgs/ft.² ;

4. a layer of yellow color-providing compound and padding Yellow GL (abenzidine yellow pigment employed as a yellow filter) dispersed ingelatin and coated at a coverage of about 40 mgs/ft.² of yellowcolor-providing compound, 50 mgs/ft.² of Padding Yellow GL and about 90mgs/ft.² of gelatin;

5. a blue-sensitive gelatino silver iodobromide emulsion coated at acoverage of about 30 mgs/ft.² of silver and about 52 mgs/ft.² ofgelatin; and

6. a layer of gelatin coated at a coverage of about 30 mgs/ft.².

A transparent polyethylene terephthalate film base was coated, insuccession, with the following layers to form an image-receivingelement:

1. a layer of the partial butyl ester of polyethylene/maleic anhydridecopolymer coated at a coverage of about 2500 mgs/ft.² ;

2. a layer containing a mixture (40:1 ratio) of a 60-30-4-6 copolymer ofbutylacrylate, diacetone acrylamide, styrene and methacrylic acid andpolyacrylamide at a coverage of about 500 mgs/ft.² ; and

3. a polymeric image-receiving layer containing a 2:1 mixture, byweight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage ofabout 300 mgs/ft.² and containing a silver halide solvent precursor ofthe formula ##STR16## at a coverage of about 50 mgs/ft.².

The photosensitive element was exposed to red and blue light andprocessed in superposed relationship with the image-receiving element byspreading an aqueous alkaline processing composition in a layerapproximately 0.0024 inch thick between the superposed elements. Theprocessing composition employed comprised:

    ______________________________________                                        Water                100.0 cc.                                                Sodium hydroxide     5.0 g.                                                   Sodium carboxymethyl                                                          cellulose            3.4 g.                                                   Chlorohydroquinone   1.3 g.                                                   Phenidone            0.7 g.                                                   Sodium sulfite       2.0 g.                                                   Titanium dioxide     50.0 g.                                                  ______________________________________                                    

As a control, a photosensitive element was prepared, exposed andprocessed as described above except that layer 3 of the photosensitiveelement was a layer of gelatin coated at a coverage of about 200mgs/ft.² and layer 4 contained 40 mgs/ft.² each of yellowcolor-providing compound and gelatin with the benzidine yellow (50mgs/ft.²) being dispersed in a separate layer of gelatin (50 mgs/ft.²)disposed between layers 4 and 5.

After a processing time of about 10 minutes, it was observed that thetest integral negative-positive reflection print of Example 1 exhibitedbetter color isolation than that of the control.

EXAMPLE 2

A photosensitive element using as the color-providing compounds torelease a magenta and a yellow dye ##STR17## was prepared by coating atransparent polyethylene terephthalate film base with the followinglayers:

1. a layer of magenta color-providing compound dispersed in gelatin andcoated at a coverage of about 50 mgs/ft.² of magenta color-providingcompound and about 50 mgs/ft.² of gelatin;

2. a green-sensitive gelatino silver iodochloride emulsion coated at acoverage of about 40 mgs/ft.² of silver and about 36 mgs/ft.² ofgelatin;

3. A layer of gelatin coated at a coverage of 15 mgs/ft.² ;

4. a layer of cadmium sulfide dispersed in gelatin and coated at acoverage of 0.34 mg/ft.² of cadmium sulfide and 5 mgs/ft.² of gelatin;

5. a layer of yellow color-providing compound and Padding Yellow GLdispersed in gelatin and coated at a coverage of about 50 mgs/ft.² ofyellow color-providing compound about 50 mgs/ft.² of Padding Yellow andabout 50 mgs/ft.² of gelatin;

6. a blue-sensitive gelatino silver iodochloride emulsion coated at acoverage of about 30 mgs/ft.² of silver and about 27 mgs/ft.² ofgelatin; and

7. a layer of gelatin coated at a coverage of about 30 mgs/ft.².

A transparent polyethylene terephthalate film base was coated, insuccession, with the following layers to form an image-receivingelement.

1. a layer of the partial butyl ester of polyethylene/maleic anhydridecopolymer coated at a coverage of about 2500 mgs/ft.² ;

2. a layer containing a mixture (40:1 ratio) of a 60-30-4-6 copolymer ofbutylacrylate, diacetone acrylamide, styrene and methacrylic acid andpolyvinylalcohol at a coverage of about 500 mgs/ft.² ; and

3. a polymeric image-receiving layer containing a 2:1 mixture, byweight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage ofabout 300 mgs/ft.².

The photosensitive element was exposed to green and blue light andprocessed in superposed relationship with the image-receiving element byspreading an aqueous alkaline processing composition in a layerapproximately 0.0032 inch thick between the superposed elements. Theprocessing composition employed comprised:

    ______________________________________                                        Water                100.0 cc                                                 Sodium hydroxide     5.0 g.                                                   Sodium carboxymethyl                                                          cellulose            3.4 g.                                                   Tetramethyl reductic acid                                                                          6.0 g.                                                   4-methylthiomethyl uracil                                                                          1.5 g.                                                   Sodium sulfite       2.0 g.                                                   Titanium dioxide     50.0 g.                                                  ______________________________________                                    

As a control, a photosensitive element was prepared, exposed andprocessed as described above except that the cadmium sulfide was omittedfrom layer 4 of the photosensitive element.

After a processing time of about 10 minutes, it was observed that thetest integral negative-positive reflection print of Example 2 exhibitedbetter color isolation than the control. After 18 hours, the integralreflection density to blue light where the test bichrome received blueexposure but no green exposure was reduced by 0.61 density units ascompared to the control, while the density to green light remainedrelatively constant being about 0.14 density units less than thecontrol. The reflection density to green light where the test bichromereceived green exposure but no blue exposure was reduced by 0.08 densityunits, while the reflection density to blue light remained substantiallythe same as the control.

EXAMPLE 3

Example 2 was repeated except that layer 3 of the photosensitive elementcontained 17.5 mgs/ft.² of gelatin and layer 4 contained 0.17 mg/ft.² ofcadmium sulfide and 2.5 mgs/ft.² of gelatin.

Compared to the same control as used in Example 2, it was found after 18hours that the integral reflection density to blue light where the testbichrome received blue exposure but no green exposure was reduced by0.47 density units, while the density to green light remained relativelyconstant being about 0.12 density units less than the control. Thereflection density to green light where the bichrome received greenexposure but no blue exposure was reduced by 0.05 density units, whilethe density to blue light remained relatively constant being about 0.13density units more than the control.

Besides the silver ion scavengers used in the above examples, it wasalso found that silver proteinate was effective as a silver ionscavenger layer for improving color isolation.

In the foregoing examples, the color-providing compounds were dispersedin gelatin as a particulate dispersion according to the proceduredescribed in U.S. Pat. No. 3,438,775.

The processing compositions employed in the present invention comprisean aqueous alkaline solution of a silver halide solvent and a silverhalide developing agent. The named ingredients may be present initiallyin the aqueous medium or may be present initially elsewhere in thephotographic product, for example, in the emulsion and/orimage-receiving and/or spacer layers as heretofore suggested in the art.When such ingredients are present initially in a layer or layers of thefilm unit, the processing composition is formed by contacting theproduct with a suitable aqueous medium to form a solution containingthese ingredients.

The alkali employed in the processing composition may be any of thealkaline material heretofore used, such as sodium or potassiumhydroxide. The silver halide solvent also may be any of the heretoforeknown materials, such as, sodium or potassium thiosulfate, sodiumthiocyanate and uracil. Also, a silver halide solvent precursor may beused, such as described in U.S. Pat. No. 3,698,898 issued Oct. 17, 1972and as used in Example 1 above. The silver halide developing agent maybe selected from those commonly employed such as the diamino benzenes,e.g., paraphenylene-diamine; aminophenols, e.g., methyl-p-aminophenol;dihydroxybenzenes, e.g., hydroquinone; and enediols, e.g., ascorbic acidand tetramethyl reductic acid. In addition to the aforementionedingredients, the composition may contain antifoggants, preservatives,viscosity-imparting reagents, and other adjuncts as conventionally usedin the art. It will be understood that the selection of the abovematerials is not critical to the practice of this invention.

In various embodiments of the present invention, other silver halideemulsions may be used, such as silver chloride, silver bromide, silverbromoiodide, silver chlorobromide and silver chlorobromoiodide. In lieuof the usual negative-working silver halide emulsions, direct positivesilver halide emulsions may be employed. By using such an emulsion inExample 1 above, for instance, a negative rather than a positivetransfer image may be produced. Typical materials that may be used asthe support for the photosensitive and image-receiving elements arepaper, glass and plastic materials, e.g., celulose nitrate, celluloseacetate, polyvinyl acetal, polystyrene, polyethyleneterephthalate,polyethylene and polypropylene.

It will be appreciated that the photographic system of the presentinvention may be used with film structures other than those illustrated.For example, in diffusion transfer film units the negative component andthe positive component may be separate elements as shown above which arebrought together during processing and thereafter either retainedtogether as the final print or separated following image formation.

Rather than the photosensitive layers and the image-receiving layerbeing in separate elements, they may be in the same element. In such afilm unit, the image-receiving layer is coated on a support and thephotosensitive layers are coated on the upper surface of theimage-receiving layer. The liquid processing composition is appliedbetween the combined negative-positive element and a spreading sheetwhich assists in spreading the liquid composition in a uniform layeradjacent the surface of the photosensitive layer.

Illustrative of still other film units are those where the negative andpositive components together may comprise a unitary structure, e.g.,integral negative-positive film units wherein the negative and positivecomponents are laminated and/or otherwise physically retained togetherat least prior to image formation. Generally, such film units comprise aplurality of essential layers including a negative component comprisinga image-receiving layer which components may be laminated together orotherwise secured together in physical juxtaposition as a singlestructure. In the formation of color transfer images, the dyeimage-providing compounds of the present invention may be associatedwith the silver halide layers of the negative component.

Included among such structures are those adapted for forming a transferimage viewable without separation, i.e., wherein the positive componentcontaining the transfer image need not be separated from the negativecomponent for viewing purposes. In addition to the aforementionedessential layers, such film units include means for providing areflecting layer between the image-receiving and negative components inorder to mask effectively the silver images formed as a function ofdevelopment of the silver halide layers and any remaining associated dyeimage-providing material and also to provide a background for viewingthe transfer image in the receiving component, without separation, byreflected light. This reflecting layer may comprise a preformed layer ofa reflecting agent included in the essential layers of the film unit orthe reflecting agent may be provided subsequent to photoexposure, e.g.,by including the light-reflecting agent in the processing composition.In addition to the aforementioned layers, such film units usuallyinclude dimensionally stable outer support layers, the transfer dyeimage being viewable through one of said supports.

These film units optionally may contain other layers capable ofperforming specific desired functions. For example, where it isdesirable to adjust the alkalinity of the environment in theimage-receiving layer following substantial transfer of the dyeimage-providing material, the pH reduction may be effected by including,preferably in the image-receiving component of the film unit, aneutralizing layer comprising an acid-reacting reagent such as apolymeric acid layer as described in U.S. Pat. No. 3,362,819. An inertinterlayer or spacer layer may be and is preferably disposed between thepolymeric acid layer and the image-receiving layer in order to controlor "time" the pH reduction. Suitable spacer or "timing" layers for thispurpose are described with particularity in U.S. Pat. Nos. 3,362,819;3,419,389; 3,421,893; 3,455,686; and 3,575,701. The image-receivinglayer may comprises any of the materials known in the art, such aspolyvinyl alcohol, gelatin, etc. and may contain agents adapted tomordant or otherwise fix the transferred image dyes. Particularly usefulmaterials comprise polyvinyl alcohol or gelatin containing a dye mordantsuch as poly-4-vinylpyridine, as disclosed in U.S. Pat. No. 3,148,061.Also, such film units usually are employed in conjunction with means,such as, a rupturable container containing the requisite processingcomposition and adapted upon application of pressure of applying itscontents to develop the exposed film unit.

It will be appreciated that the expression "color" as used throughoutthe foregoing specification and in the appended claims is intended toinclude the use of a plurality of colors to obtain black.

Since certain changes may be made in the above products and processeswithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. A photographic product which comprises aphotosensitive element comprising a plurality of layers including asupport, at least two selectively sensitized silver halide emulsionlayers, each of said emulsion layers having associated therewith acolor-providing compound capable of undergoing cleavage in the presenceof an imagewise distribution of silver ions and/or soluble silvercomplex to liberate a color-providing moiety in an imagewisedistribution corresponding to said distribution of silver ions and/orsaid complex, one of said color-providing compound and saidcolor-providing moiety being diffusible in aqueous alkaline solution andthe other being substantially non-diffusible in aqueous alkalinesolution, and a scavenger layer containing a scavenger for silver ionand/or soluble silver complex, said scavenger layer being positionedbetween said two selectively sensitized silver halide emulsion layers,each of said color-providing compounds being a compound containing agroup selected from ##STR18##
 2. A product as defined in claim 1 whereinsaid selectively sensitized emulsion layers are a red-sensitiveemulsion, a green-sensitive emulsion, and a blue-sensitive emulsion, andsaid color-providing compounds associated with said silver halideemulsions are, respectively, a cyan color-providing compound, a magentacolor-providing compound and a yellow color-providing compound.
 3. Aproduct as defined in claim 2 which includes a first scavenger layerpositioned between said red-sensitive and said green-sensitive silverhalide emulsions and a second scavenger layer positioned between saidgreen-sensitive and said blue-sensitive silver halide emulsions.
 4. Aproduct as defined in claim 1 wherein said scavenger layer comprises asilver complexing agent capable of forming a non-diffusible silvercomplex.
 5. A product as defined in claim 1 wherein said scavenger layercomprises a silver complexing agent capable of forming a silver complexdecomposable to a silver precipitating agent.
 6. A product as defined inclaim 1 wherein said scavenger layer comprises a silver precipitatingagent.
 7. A product as defined in claim 6 wherein said scavenger layercomprises a silver precipitating agent dispersed in a layer of gelatin.8. A product as defined in claim 4 wherein said silver complexing agentis a polymer containing mercapto groups.
 9. A product as defined inclaim 1 wherein each said color-providing compound contains the groups##STR19##
 10. A product as defined in claim 10 wherein X is ##STR20##11. A product as defined in claim 10 wherein each said compound is acyclic compound having a ring system containing up to 20 members andsaid ##STR21## group is included in the ring.
 12. A product as definedin claim 11 wherein each said color-providing compound is athiazolidine.
 13. A product as defined in claim 1 wherein each saidcolor-providing compound is substantially non-diffusible and saidcolor-providing moiety released therefrom is diffusible in aqueousalkaline solution.
 14. A product as defined in claim 13 wherein eachsaid color-providing moiety liberated from each said color-providingcompound is a diffusible dye.
 15. A product as defined in claim 14including a superposed image-receiving layer so positioned as to becapable of receiving by diffusion transfer an imagewise distribution ofeach said diffusible dye and further including means for applying anaqueous alkaline processing composition in a substantially uniform layerbetween said silver halide emulsions and said image-receiving layer. 16.A product as defined in claim 15 wherein said image-receiving layer iscarried on a transparent support and said product additionally includesmeans for providing a light-reflecting layer between saidimage-receiving layer and said silver halide emulsions to mask saidsilver halide emulsions after development thereof and to provide a whitebackground for viewing a dye image in said image-receiving layer.
 17. Aproduct as defined in claim 16 wherein said silver halide emulsions areadapted to be exposed through said transparent support.
 18. A product asdefined in claim 17 wherein said means for providing an aqueous alkalineprocessing composition comprises a rupturable container releasablyretaining an aqueous alkaline solution of a silver halide developingagent positioned between said image-receiving layer and said silverhalide emulsions.
 19. A product as defined in claim 18 wherein saidmeans for providing a light-reflecting layer comprise a white pigmentdispersed in said processing composition.
 20. A photographic process forforming multicolor images comprising the steps ofa. exposing aphotosensitive element comprising a plurality of layers including asupport, at least two selectively sensitized silver halide emulsionlayers, each of said emulsion layers having associated therewith, acolor-providing compound capable of undergoing cleavage in the presenceof an imagewise distribution of silver ions and/or soluble silvercomplex to liberate a color-providing moiety in an imagewisedistribution corresponding to said distribution of silver ions and/orsaid complex, one of said color-providing compound and saidcolor-providing moiety being diffusible in aqueous alkaline solution andthe other being substantially non-diffusible in aqueous alkalinesolution, and a scavenger layer containing a scavenger for silver ionand/or soluble silver complex, said scavenger layer being positionedbetween said two selectively sensitized silver halide emulsion layers,each of said color-providing compounds being a compound containing agroup selected from ##STR22## b. applying an aqueous alkaline processingcomposition to said photosensitive element to provide an aqueousalkaline solution of a silver halide developing agent and a silverhalide solvent therein, thereby developing said photosensitive element;c. forming in undeveloped areas of each of said emulsions an imagewisedistribution of silver ions and/or soluble silver complex; and d.contacting said imagewise distribution of silver ions and/or solublesilver complex formed in each of said emulsion with the emulsion'sassociated color-providing compound thereby forming correspondingimagewise distributions of each of said color-providing moieties.
 21. Aprocess as defined in claim 20 wherein said selectively sensitizedemulsion layers are a red-sensitive emulsion, a green-sensitiveemulsion, and a blue-sensitive emulsion, and said color-providingcompounds associated with said silver halide emulsions are,respectively, a cyan color-providing compound, a magenta color-providingcompound and a yellow color-providing compound.
 22. A process as definedin claim 21 which includes a first scavenger layer positioned betweensaid red-sensitive and said green-sensitive silver halide emulsions anda second scavenger layer positioned between said green-sensitive andsaid blue-sensitive silver halide emulsions.
 23. A process as defined inclaim 20 wherein said scavenger layer comprises a silver complexingagent capable of forming a non-diffusible silver complex.
 24. A processas defined in claim 20 wherein said scavenger layer comprises a silvercomplexing agent capable of forming a silver complex decomposable to asilver precipitating agent.
 25. A process as defined in claim 20 whereinsaid scavenger layer comprises a silver precipitating agent.
 26. Aprocess as defined in claim 25 wherein said scavenger layer comprises asilver precipitating agent dispersed in a layer of gelatin.
 27. Aprocess as defined in claim 26 wherein said precipitating agent iscadmium sulfide.
 28. A process as defined in claim 23 wherein saidsilver complexing agent is a polymer containing mercapto groups.
 29. Aprocess as defined in claim 20 wherein each said color-providingcompound contains the groups ##STR23##
 30. A process as defined in claim29 wherein X is ##STR24##
 31. A process as defined in claim 30 whereineach said compound is a cyclic compound having a ring system containingup to 20 members and said ##STR25## group is included in the ring.
 32. Aprocess as defined in claim 31 wherein each said color-providingcompound is a thiazolidine.
 33. A process as defined in claim 20 whereineach said color-providing compound is substantially non-diffusible andeach said color-providing moiety released therefrom is diffusible inaqueous alkaline solution.
 34. A process as defined in claim 33 whereineach said color-providing moiety liberated from each saidcolor-providing compound is a diffusible dye.
 35. A process as definedin claim 34 wherein a sheet-like element comprising an image-receivinglayer is superposed with said photosensitive element and at least aportion of said imagewise distributions of each of said diffusible dyesis transferred to said image-receiving layer to form a color transferimage thereon.
 36. A process as defined in claim 35 wherein said aqueousalkaline processing composition is distributed in a substantiallyuniform layer between said image-receiving layer and said silver halideemulsions.
 37. A process as defined in claim 36 wherein saidimage-receiving layer is carried on a transparent support.
 38. A processas defined in claim 37 which includes providing a light-reflecting layerbetween said image-receiving layer and said silver halide emulsions tomask said silver halide emulsions after development thereof and toprovide a white background for viewing the dye image in saidimage-receiving layer.
 39. A process as defined in claim 38 wherein saidlight-reflecting layer is provided by including a white pigmentdispersed in said processing composition.
 40. A process as defined inclaim 39 which includes the step of maintaining said photosensitiveelement and said sheet-like element intact subsequent to processing. 41.A process as defined in claim 35 wherein said selectively sensitizedemulsion layers are a red-sensitive emulsion, a green-sensitiveemulsion, and a blue-sensitive emulsion, and said color-providingcompounds associated with said silver halide emulsions are,respectively, a cyan color-providing compound, a magenta color-providingcompound and a yellow color-providing compound.
 42. A process as definedin claim 41 which includes a first scavenger layer positioned betweensaid red-sensitive and said green-sensitive silver halide emulsions anda second scavenger layer positioned between said green-sensitive andsaid blue-sensitive silver halide emulsions.
 43. A process as defined inclaim 35 wherein said scavenger layer comprises a silver complexingagent capable of forming a non-diffusible silver complex.
 44. A processas defined in claim 35 wherein said scavenger layer comprises a silvercomplexing agent capable of forming a silver complex decomposable to asilver precipitating agent.
 45. A process as defined in claim 35 whereinsaid scavenger layer comprises a silver precipitating agent.
 46. Aprocess as defined in claim 45 wherein said scavenger layer comprises asilver precipitating agent dispersed in a layer of gelatin.
 47. Aprocess as defined in claim 46 wherein said silver precipitating agentis cadmium sulfide.
 48. A process as defined in claim 43 wherein saidsilver complexing agent is a polymer containing mercapto groups.
 49. Aprocess as defined in claim 41 wherein each said color-providingcompound contains the group ##STR26##
 50. A process as defined in claim49 wherein X is ##STR27##
 51. A process as defined in claim 50 whereineach said compound is a cyclic compound having a ring system containingup to 20 members and said ##STR28## group is included in the ring.
 52. Aprocess as defined in claim 51 wherein each said color-providingcompound is thiazolidine.